Quinones, such as ubiquinone and plastoquinone, participate as oxidation-reduction components in the mitochondrial respiratory chain of all aerobic cells and in the analogous electron transfer processes of chloroplasts and photosynthetic bacteria. In addition, the oxidation and reduction of quinones are hydrogen transfer processes. Consequently, as the chemiosmotic mechanism of oxidative and photosynthetic phosphorylation has become established, it has become increasingly apparent that quinones may fulfill a uniquely important role in these energy conserving processes, in that the release and uptake of protons coincident with oxidation and reduction of quinones may constitute the primary energy conserving steps whereby active transport of protons is chemically coupled to energy releasing electron transfer reactions. The purpose of this proposal is to convene an international conference devoted to the function of quinones in electron transfer and energy-conserving systems. The conference will consist of an interdisciplinary group of biochemists, chemists, and biophysicists whose research will most likely benefit from a timely exchange of currently available information and an assessment of the outstanding problems in this rapidly evolving area of investigation.